I also see the warnings. In my case it's because I'm using outline-minor mode in an elisp file. I'm not sure it's supported, but it worked years ago: I could fold and unfold sections with usual org-mode keys like C-tab. I miss that feature. I never managed to learn the real outline-mode keys/concepts (outline-show-branches, outline-hide-subtree etc.).
To reproduce it, I used test.el with:
;; -*- mode: emacs-lisp; mode:outline-minor; hs-minor-mode: nil; outline-regexp:";;;;* [^ \n]" -*-
;; a
;;; a1
;; b
Then I went to ;; a and pressed C-tab, expecting to open/close that section (showing/hiding the a1). And I saw the warning, and an error: rx--translate-bounded-repetition: rx ‘**’ range error [3 times]
Please excuse if my expectations or my test file are broken. I didn't use this feature in years.